Furthermore, the invention relates to a structural element, in particular made from a fiber-reinforced plastic composite material.
From DE 10 151 383 A1 an assembly for compensating a tolerance between two components is known. Said assembly comprises a screw which is plugged through the two components. The screw head is supported on the first component. The screw is screwed into a nut on the other component. In addition, a compensating bush is provided, having a through bore and an external thread to match the internal thread of the nut. The compensating bush also comprises a clamping portion, by means of which the compensating bush can be frictionally engaged with the screw, whereas it is rotatable relative to the screw upon overcoming the friction fit. When the screw is plugged in the compensating bush and is rotated, the compensating bush can rotate due to the friction fit. Thereby, the compensating bush is unscrewed from the nut in the opposite direction of the plug-in direction for the purpose of tolerance compensation. When the compensating bush abuts on the first component, the former is screwed with an internal thread for clamping the two components.
DE 10 2008 055 526 A1 and DE 10 2007 037 242 A1 describe other devices of this type.
WO 2013150016 A1 discloses a fastening element for connecting two components with automatic tolerance compensation between the components. The fastening element comprises a base element fixable in an opening of the one component and an adjusting element that can be screwed to the internal thread of the base element via an external thread. Adjacent to the internal thread, the base element comprises a second (internal) thread portion for screwing in a fastening screw having a hand of thread opposite to the hand of thread of the thread. On the inside, the adjustment element comprises entraining elements establishing a friction fit between the screw and the adjusting element upon screwing in of the screw. When the screw is screwed in the thread portion, the adjusting element is rotated via the entraining elements, whereby depending on the rotational direction of the screw the adjusting element is moved away from or towards the base element in axial direction, due to which the tolerance compensation can be obtained. According to an alternative embodiment, the base element can be stuck in the opening of the one component.
In this prior art, the screw head of the screw is supported on the component. As a disadvantage, the component can be damaged by the tightening moment of the screw. This is of particular disadvantage if the component is made from a fiber composite material. In addition, given the lack of space, the known device would be unsuitable for supporting composite components. Finally, the projecting screw head affects the appearance of the visible surface of the component.
Therefore, the known embodiments are not suited for many applications, in particular in the aircraft construction. For reasons of stability and load capacity, it is disadvantageous for the support of structural components made from composite materials if the connection screw is fixed with the screw head on the upper side of the composite material. In addition, the tolerance compensation arrangement in the prior art, cf. e. g. DE 101 51 383 A1, is connected to the nut of the holding element. Such an embodiment, however, would be unsuitable or unfavorable for the support of composite components due to lack of space.
Accordingly, the aim of the present invention is to indicate a device of the above cited kind, by means of which the problems of the prior art can be reduced or avoided. In particular, it is the aim of the invention to design the device for a tolerance compensation in the case of structural elements made from composite materials.
To achieve this aim, a device and a structural element are provided, the device for a spaced apart connection of a structural element with a holding element by means of a connection screw, with a distance compensation element comprising a longitudinal bore for the passage of the connection screw, and with an entraining element arranged in the longitudinal bore, in which the entraining element is connected to the connection screw by means of a friction fit, so that the distance compensation element is transferred into an abutment position bridging the distance between the structural element and the holding element by screwing in of the connection screw, wherein the distance compensation element is connected to an insertion part via a screw connection, in which the insertion part comprises a fastening section that is arranged within the structural element for bonding with the structural element.
In accordance with the invention, the distance compensation element is therefore connected to an insertion part via a screw connection, which insertion part comprises a fastening section that can be arranged within the structural element for bonding with the structural element.
In the mounted state, the fastening section of the insertion part is therefore accommodated in a recess of the structural element and immovably fixed to the adjacent material of the structural element by means of an adhesive joint. Therefore, the insertion part preferably does not project beyond the outer surface of the structural element facing away from the holding element. Therefore, the fastening section is preferably essentially completely integrated in the structural element which preferably comprises a panel made from a composite material. In addition, a surface material, in particular a veneer can be provided on the structural element comprising the composite panel. The insertion part comprises an adhesive surface on the fastening section for bonding with a corresponding adhesive surface of the structural element limiting the recess of the structural element. The embodiment according to the invention has the particular advantage of that a point loading in the structural element is avoided, which in the prior art is caused by the connection screw supported on the outer surface of the component. In addition, a particular robust embodiment is provided, complying with high safety standards. In addition, it is of advantage that the visible surface of the structural element is hardly affected by the arrangement of the distance compensation element, since the projecting screw head in the prior art is missing. In addition, by the connection of the distance compensation element to the insertion part—in contrast to the connection to the nut of the holding element in the prior art—an especially space-saving embodiment can be obtained, which is of particular advantage for structural elements made from fiber-reinforced plastic composite materials (composite components). In this embodiment, the holding element can be equipped with a comparatively small nut. Therefore, the device according to the invention can be used with special advantages for the mounting of structural elements made from fiber-reinforced plastic material, which structural elements in particular have a wall strength or thickness of 5 to 15 mm.
To bridge the distance between the structural element and the holding element, it is favorable that the distance compensation element can be transferred from a distance position toward the holding element into the abutment position on the holding element upon screwing in of the connection screw. In this embodiment, the distance compensation element is unscrewed from the insertion part when the connection screw is screwed in. Accordingly, the rotational movement of the connection screw is converted into an extension of the device, the free end of the distance compensation element forming the abutment surface moving toward the holding element. Upon reaching the abutment position, the friction fit between the connection screw and the entraining element is overcome, so that the connection screw can be twisted with respect to the entraining element. Subsequently, the connection screw can be fixed to a thread of the holding element.
To obtain a stable adhesive joint between the insertion part and the structural element it is favorable if the insertion part comprises at least one fastening flange on the fastening section, which flange can be arranged between the outer surfaces of the structural element for bonding of the insertion part with the structural element, the at least one fastening flange preferably extending essentially perpendicularly to the longitudinal axis of the longitudinal bore. In the manufacture, the fastening flange is fixed to the structural element by means of an adhesive joint, thus obtaining an intimate bond. On the one hand, the arrangement of the fastening flange facilitates the application of the adhesive. On the other hand, the fastening flange effects a particularly reliable safeguard against torsional forces applying on the device during operation. Preferably, the fastening flange is arranged essentially flush with a surface of a composite panel of the structural element.
One embodiment is particularly favorable, in which the insertion part comprises two especially parallel and spaced-apart fastening flanges on the fastening section. Thus, a particularly stable arrangement of the insertion part within the recess of the structural element can be obtained. The fastening flanges are preferably arranged essentially completely between the outer surfaces of the structural element, at least one of the fastening flanges expediently terminating essentially flush with a surface of a composite-material panel of the structural element. A cavity is formed between the fastening flanges for the reception of the adhesive, by means of which the insertion part is mounted in the structural element. For supporting the structural element, first of all the structural element can be provided with a bore having the outer diameter of the fastening flanges. After inserting the insertion part the ring-shaped cavity between the fastening flanges can be filled with adhesive. The adhesive between the fastening flanges bonds with the material, in particular the composite material, of the structural element.
For bonding of the insertion part with the structural element it is favorable if at least one of the fastening flanges comprises at least one opening, in particular at least one notch on an outer edge of the fastening flange for introducing the adhesive between the fastening flanges. One of the fastening flanges preferably has two opposite notches for filling in of the adhesive. Depending on the design, the two fastening flanges may also comprise at least one opening each for insertion of the adhesive.
To determine the maximum adjustability of the device it is favorable if stops for limiting the movement of the distance compensation element are provided in the axial direction relative to the insertion part. Therefore, the device may be adjusted by twisting the connection screw between a shorter state, in which the distance compensation element projects less far from the insertion part, and a longer state, in which the distance compensation element projects further from the insertion part, the stops blocking any adjustment of the distance compensation element beyond reaching the shorter or longer state.
For manufacturing reasons, it is preferred if the distance compensation element comprises a receiving opening for detachably receiving an abutment element, by means of which unscrewing the distance compensation element from of the insertion part can be blocked in the mounted state. Due to the detachable arrangement of the abutment element in the receiving opening the device can be mounted and/or removed in a particularly simple manner.
In this embodiment, it is favorable if a particularly U-shaped clip element is provided as an abutment element, which clip element in the mounted state projects into the longitudinal bore of the distance compensation element. The clip element can be inserted with its ends in the corresponding receiving openings of the distance compensation element. In the mounted state, the clip element blocks any adjustment of the distance compensation element beyond reaching the second state of the device, the second state having the maximum length. With respect to a particularly cheap and simple construction the clip element provided may be a wire, in particular with a circular cross-section, the recesses of the distance compensation element being designed accordingly. The clip element is preferably elastically deformable, so that in the mounted state the clip element can be secured against unintentional removal by means of elastic deformation of the ends of the clip element which are plugged through the receiving openings.
For a non-rotatable connection between the connection screw and the distance compensation element upon screwing in the connection screw, it is favorable if a spring element which is elastically deformable by means of the connection screw is provided as an entraining element. In engagement with the connection screw the spring element is deformed elastically, the restoring forces of the spring element effecting a friction fit between the connection screw and the spring element. Upon reaching the abutment position on the holding element, frictional forces will occur between the abutment surface of the distance compensation element and the holding element, so that the friction fit between the connection screw and the spring element is overcome when the connection screw is further twisted. In this state, the connection screw can be fixed in the corresponding thread of the holding element.
To be able to reliably ensure entrainment of the distance compensation element upon screwing in the connection screw, it is of advantage if the spring element is arranged in a holding section of the distance compensation element in a torque-proof and axially immovable manner. For this purpose, it is favorable if the spring element and the longitudinal bore of the distance compensation element have different cross-sectional shapes. Furthermore, the holding section may have a cross-sectional shape that is different from an adjacent portion of the longitudinal bore.
To obtain the friction fit between the connection screw and the distance compensation element it is favorable if the spring element comprises two expansion legs that can be spread by means of the connection screw and are arranged essentially in parallel to one another, which expansion legs are connected to one another via a connecting section. The expansion legs can be pressed outwards in engagement with the connection screw in an essentially perpendicular manner to the principal plane of the expansion legs, the restoring forces of the expansion legs causing a friction fit between the connection screw and the spring element. The connecting section preferably comprises two connecting legs arranged at an obtuse angle to one another, which may facilitate deformation of the expansion portions.
In accordance with a preferred embodiment a bush element is provided as an insertion part, which bush element comprises an internal thread for connection with a corresponding external thread of the distance compensation element. Advantageously, the device is thereby blocked in the abutment position on the holding element against forces in the longitudinal direction of the distance compensation element, so that in operation the device is reliably retained in the abutment position.
The distance compensation element preferably comprises, on the one end, a foot part for abutment on the holding element and, on the other end, a head part comprising the external thread, the foot part and the head part being connected to one another via a longitudinal section having a cross-sectional surface which is smaller in comparison to the foot part and the head part. For manufacturing reasons, it is preferred if the distance compensation element, in particular its head part, foot part, and connecting section, is designed as one piece.
The structural element according to the invention comprises a recess in which the above-described device is glued in place. Accordingly, the fastening section of the insertion part is arranged within the structural element. The structural element may also include several recesses, which are provided with a corresponding number of the devices described above for distance compensation. An especially stable, permanent connection between the insertion part and the structural element may be provided by means of the adhesive joints.
If the fastening section of the insertion part is arranged essentially completely within the recess of the structural element, the device may advantageously be integrated in the structural element.
The advantages of the invention may be used in particular in such applications in which a plate element, in particular a panel for aircraft equipment such as storage compartments, kitchens, lavatories, washrooms, as well as aircraft cladding elements in passenger cabins, is provided, the fastening section of the insertion part being arranged between the outer surfaces of the plate element. Such plate-shaped structural elements may be provided in various applications in the aircraft construction.
The holding element preferably comprises a nut, in particular a clip nut for connection with the connection screw, wherein the nut may preferably have a particularly small size due to the connection of the distance compensation element with the insertion part.